21115400265 has 12 divisors (see below), whose sum is σ = 36600027204. Its totient is φ = 11261546784.

The previous prime is 21115400197. The next prime is 21115400291. The reversal of 21115400265 is 56200451112.

21115400265 is a `hidden beast` number, since 2 + 111 + 540 + 0 + 2 + 6 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 4343337216 + 16772063049 = 65904^2 + 129507^2 .

It is not a de Polignac number, because 21115400265 - 2¹¹ = 21115398217 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 234615514 + ... + 234615603.

It is an arithmetic number, because the mean of its divisors is an integer number (3050002267).

Almost surely, 2^21115400265 is an apocalyptic number.

It is an amenable number.

21115400265 is a deficient number, since it is larger than the sum of its proper divisors (15484626939).

21115400265 is a wasteful number, since it uses less digits than its factorization.

21115400265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 469231128 (or 469231125 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

Adding to 21115400265 its reverse (56200451112), we get a palindrome (77315851377).

The spelling of 21115400265 in words is "twenty-one billion, one hundred fifteen million, four hundred thousand, two hundred sixty-five".